MIPS: Add perf counter feature

Add CPU feature for standard MIPS r2 performance counters, as determined
by the Config1.PC bit. Both perf_events and oprofile probe this bit, so
lets combine the probing and change both to use cpu_has_perf.

This will also be used for VZ support in KVM to know whether performance
counters exist which can be exposed to guests.

[ralf@linux-mips.org: resolve conflict.]

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Robert Richter <rric@kernel.org>
Cc: linux-mips@linux-mips.org
Cc: oprofile-list@lists.sf.net
Patchwork: https://patchwork.linux-mips.org/patch/13226/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/include/asm/cpu.h b/arch/mips/include/asm/cpu.h
index ddcb2ab..3971a25 100644
--- a/arch/mips/include/asm/cpu.h
+++ b/arch/mips/include/asm/cpu.h
@@ -408,6 +408,7 @@
 #define MIPS_CPU_BADINSTR	MBIT_ULL(44)	/* CPU has BadInstr register */
 #define MIPS_CPU_BADINSTRP	MBIT_ULL(45)	/* CPU has BadInstrP register */
 #define MIPS_CPU_CTXTC		MBIT_ULL(46)	/* CPU has [X]ConfigContext registers */
+#define MIPS_CPU_PERF		MBIT_ULL(47)	/* CPU has MIPS performance counters */
 
 /*
  * CPU ASE encodings